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# 1.6A: Field of a Point Charge

It follows from equation 1.5.3 and the definition of electric field intensity that the electric field at a distance $$r$$ from a point charge $$Q$$ is of magnitude

$\tag{1.6.2}E=\frac{Q}{4\pi\epsilon_0 r^2}.$

This can be written in vector form:

$\textbf{E}=\frac{Q}{4\pi\epsilon_0 r^2}\hat{\textbf{r}}=\frac{Q}{4\pi \epsilon_0 r^3}\textbf{r}.\tag{1.6.3}$

Here $$\hat{\textbf{r}}$$ is a unit vector in the radial direction, and $$\textbf{r}$$ is a vector of length $$r$$ in the radial direction.